We present a case series of ten metal-on-polyethylene total hip
arthroplasties (MoP THAs) with delayed dislocation associated with
unrecognised adverse local tissue reaction due to corrosion at the
trunnion and pseudotumour formation. The diagnosis was not suspected in nine of the ten patients (six
female/four male; mean age 66 years), despite treatment in a specialist
unit (mean time from index surgery to revision was 58 months, 36
to 84). It was identified at revision surgery and subsequently confirmed
by histological examination of resected tissue. Pre-operative assessment
and culture results ruled out infection. A variety of treatment
strategies were used, including resection of the pseudotumour and
efforts to avoid recurrent dislocation. Aims
Methods
The October 2015 Hip &
Pelvis Roundup. 360 . looks at: Smoking and complications in arthroplasty; Smoking cessation beneficial in arthroplasty; Intermediate care and arthroplasty; Do we still need cell salvage?; Femoroacetabular impingement in the Japanese population; Trunnionosis or
Tribocorrosion at the head–neck taper interface
– so-called ‘taperosis’ – may be a source of metal ions and particulate
debris in metal-on-polyethylene total hip arthroplasty (THA). We examined the effect of femoral head length on fretting and
corrosion in retrieved head–neck tapers Head length was observed to affect fretting (p = 0.03), with
28 mm + 8 mm femoral heads showing greater total fretting scores
than all other head lengths. The central zone of the femoral head
bore taper was subject to increased fretting damage (p = 0.01),
regardless of head length or stem offset. High-offset femoral stems
were associated with greater total fretting of the bore taper (p
= 0.04). Increased fretting damage is seen with longer head lengths and
high-offset femoral stems, and occurs within a central concentric
zone of the femoral head bore taper. Further investigation is required
to determine the effect of increased head size, and variations in
head–neck taper design. Cite this article:
A modular femoral head–neck junction has practical
advantages in total hip replacement. Taper fretting and corrosion
have so far been an infrequent cause of revision. The role of design
and manufacturing variables continues to be debated. Over the past
decade several changes in technology and clinical practice might
result in an increase in clinically significant taper fretting and
corrosion. Those factors include an increased usage of large diameter
(36 mm) heads, reduced femoral neck and taper dimensions, greater
variability in taper assembly with smaller incision surgery, and
higher taper stresses due to increased patient weight and/or physical
activity. Additional studies are needed to determine the role of
taper assembly compared with design, manufacturing and other implant
variables. Cite this article:
